[Study of the organization of sensorimotor stages in man using delayed evoked potentials]

The main aim of this study was to test the relative organization of three of the stages of Sanders' 1990 information processing model: "features extraction", "response choice", and "motor adjustment". The variables influencing these stages: stimulus degradation, stimulus-response (SR) compatibility and preparatory period have been manipulated. Event related potentials (N100, N200, P300) and reaction time were recorded from ten healthy subjects, in a dichotic listening task. Reaction times are lengthened for degraded stimuli, in the absence of a preparatory period and for SR non compatible conditions. However, the interaction between preparatory period and stimulus degradation variables, suggests an overlapping of the corresponding stages contrary to Sanders' postulate. The non compatible condition increases the latency of N200 and P300 components. The results suggest that the response choice processing would be contemporary to the N200 component. They are discussed within the framework of models of early communication between sensory and motor systems.